JP2519244Y2 - Tandem negative pressure booster - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Field of Industrial Application The present invention relates to a tandem-type negative pressure booster used for operating a brake master cylinder of an automobile, and more particularly to a booster shell. A partition plate for partitioning the interior into a front shell chamber and a rear shell chamber is provided, and a front booster piston in which the diaphragm is polymer-bonded to the rear surface, and a rear booster piston in which the rear diaphragm is polymer-bonded to the rear surface. However, the present invention relates to an improvement of a device which is slidably supported by the partition plate and is connected via a piston boss connected to the output rod.

(2) Conventional Technology Such a tandem type negative pressure booster is disclosed in
It is already known as disclosed in Japanese Patent No. 100569.

(3) Problem to be Solved by the Invention In the above-mentioned conventional one, the piston boss is divided into two parts, the half body and the rear half body, and the rear booster piston is connected to the rear half body by a screw member or the like. At the same time, the front half body is engaged, and the front booster piston is sandwiched between the rear booster piston and the front half body. For this reason, a seal member is required to achieve a seal between the front half body and the rear half body.

The present invention has been made in view of such circumstances,
An object of the present invention is to provide a tandem-type negative pressure booster having a structure in which the piston boss is prevented from being divided and a seal member is not required, and the front and rear booster pistons can be bonded to the piston boss with a simple structure.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, according to the present invention, a front engaging portion that engages with a piston boss from the front side and a piston boss from the rear side. A rear connecting diaphragm, which has a plurality of rear engaging portions that can be bent to engage with each other and extends rearward, is connected to the central portion of the front booster piston and encloses the inner peripheral edge of the rear booster piston. Of the inner peripheral bead is abutted from the rear on the piston boss through the rear engaging portion, a stopper for elastically pushing the inner peripheral bead forward is engaged with the piston boss, and the inner peripheral edge portion of the partition plate. A seal member is provided between the outer surface of the connecting cylinder and the outer surface of the connecting cylinder.

(2) Operation According to the above configuration, by engaging the front engaging portion with the piston boss from the front side and bending the rear engaging portion to engage with the piston boss from the rear side, the front booster piston is provided. The rear booster piston can be engaged with the piston boss by elastically urging the inner peripheral bead of the rear diaphragm toward the piston boss from the rear with a stopper that engages with the piston boss. Can be done without splitting the piston boss,
Both booster pistons can be attached to the piston boss.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention, and FIG. 1 is a vertical side view of a tandem type negative pressure booster,
FIG. 2 is a sectional view taken along line II-II in FIG.

First, in FIG. 1, a brake master cylinder M operated by the booster B is attached to the front surface of the booster shell 1 in the tandem type negative pressure booster B.

The booster shell 1 is sandwiched between a pair of front and rear shell halves 1a and 1b that connect opposite ends to each other and both shell halves 1a and 1b so that the inside of the booster shell 1 is a front shell chamber 2 and a rear shell chamber. The rear shell half 1b is supported by a supporting portion S such as a vehicle body.

The front shell chamber 2 has a front booster piston 4 housed therein so as to be capable of reciprocating back and forth, and a front portion which is polymer-bonded to the rear surface thereof and is also sandwiched between the front shell half body 1a and the partition plate 1c. The diaphragm 5 and the front negative pressure chamber 2a on the front side
And a front working chamber 2b on the rear side. Further, the rear shell chamber 3 includes the rear booster piston 6 housed in the rear shell chamber 3 so as to be able to reciprocate back and forth, and the partition plates 1c together with both shell halves 1a, 1b.
A rear diaphragm 7 fixed in between and superposed on the rear surface of the rear booster piston 6 divides it into a front rear negative pressure chamber 3a and a rear rear working chamber 3b.

A piston boss 8 made of synthetic resin is supported on the booster shell 1 so as to be slidable back and forth. This piston boss 8
Is a disk-shaped main body portion 8a, a valve cylinder portion 8b extending rearward from the main body portion 8a, and a flange portion protruding outward in the radial direction from the outer periphery of the axially intermediate portion of the main body portion 8a. With 8c. On the other hand, on the rear wall of the booster shell 2, a rear extension cylinder 9 extending rearward is integrally provided so as to project, and the valve cylinder portion 8b is provided.
Is slidably supported on the rear extension cylinder 9 via a bush 10 and a seal member 11. Further, the front booster piston 4 is formed of a steel plate in an annular shape, and at the center of the front booster piston 4, a cylindrical connecting tube 12 extending rearward so as to be engaged with the piston boss 8. Are integrally connected to each other, and the connecting cylinder 12 is slidably supported by the inner peripheral portion of the partition plate 1c via a bush 13 and a seal member 14.

Thus, the connecting cylinder 12, that is, the front booster piston 4,
The rear booster piston 6 formed in an annular shape by a steel plate is connected to the piston boss 8 as follows.

Referring also to FIG. 2, the inner diameter of the connecting cylinder 12 is set so that the front side of the flange portion 8c of the main body portion 8a of the piston boss 8 can be fitted. Moreover, at the rear end (right end in FIG. 1) of the connecting cylinder 12, rear engaging portions 12b are provided so as to project rearward at a plurality of circumferentially spaced locations, for example, four locations. The rear ends of the connecting cylinders 12 between the joining portions 12b form front engaging portions 12a.
That is, four front engaging portions 12a ... Which are arc-shaped are formed at the front end of the connecting cylinder 12 except the rear engaging portions 12b.
The front engaging portions 12a ... Abut on and engage with the base portion of the flange portion 8c of the piston boss 8 from the front side. On the other hand, in the piston boss 8, each of the rear engaging portions 12
Insertion holes 15 through which the rear engaging portions 12b are inserted are formed in the portions corresponding to b, and the rearward protruding portions of the rear engaging portions 12b that are inserted into the respective insertion holes 15 ... The edge is
It is bent to engage the rear surface of the flange portion 8c.

The inner peripheral bead 7a of the rear diaphragm 7a is formed so as to wrap around the inner peripheral edge of the rear booster piston 6,
The flange booster 8c is brought into contact with the rear surface of the flange booster 8c. Thus, the bent portion of each rear engaging portion 12b ... Is sandwiched between the inner peripheral bead 7a and the flange portion 8c.

Furthermore, an annular engagement groove 16 is provided on the outer surface of the main body portion 8a of the piston boss 8 rearward of the flange portion 8c, and a stopper 17 engaged with the engagement groove 16 is provided on the inner peripheral bead 7a. Abut on from the rear side. This stopper 17
The inner peripheral portion has a chrysanthemum and is formed in a ring shape, and by engaging the chrysanthemum with the engagement groove 16, the stopper 17 presses the inner peripheral bead 7a against the flange portion 8c. Demonstrates elastic force in the direction.

The front negative pressure chamber 2a is connected via a negative pressure introducing pipe 19 to a negative pressure source (not shown) (for example, inside the intake manifold of the internal combustion engine). Further, the front negative pressure chamber 2a and the rear negative pressure chamber 3a communicate with the inside of the valve cylinder portion 8b via a bifurcated first port 20 formed in the piston boss 8, and the front working chamber 2b and the rear both The working chamber 3b communicates with each other through a communication hole 21 and a communication pipe 22 formed in the piston boss 8, and also communicates with the inside of the valve tube portion 8b through a second port 23 formed in the piston boss 8. To do. The communication hole 21 is bored along the axial direction at a portion of the main body portion 8a of the piston boss 8 near the outer periphery. Further, a hole 24 is formed in a portion of the connecting cylinder 12 corresponding to the front working chamber 2b, and both ends of the communication pipe 22 bent and formed in a substantially L shape are airtight to the communication hole 21 and the hole 24. Is fitted to.

The second port 23 is connected to the first port 21 by the control valve 26.
And an atmosphere introducing port 27 opening to the end wall 9a of the rear extension cylinder 9
And communication are switched alternately.

An input rod 29 connected to the brake pedal 28 is provided in the valve tube portion 8b.
And the control valve 26 controlled thereby is provided as follows. In other words, the valve piston is
30 is slidably fitted, and the spherical front end of the input rod 29 penetrating the atmosphere introduction port 27 is provided at the center of the valve piston 30.
29a is fitted. An annular groove 30a facing the opening end of the second port 21 is formed on the outer periphery of the intermediate portion of the valve piston 30, and the bottom wall of the annular groove 30 is caulked at several points to input the valve piston 30. The spherical front end portion 29a of the rod 29 is swingably coupled.

An annular first valve seat 31 is provided on the inner peripheral surface of the valve tube portion 8b so as to project, and an annular second valve seat 32 surrounded by the first valve seat 31 is formed on the rear end surface of the valve piston 30. A rubber valve element 33 that cooperates with these valve seats 31 and 32 is disposed in the valve tube portion 8b. Thus, the valve element 33 has a tubular shape with both front and rear ends opened, and the rear end portion, that is, the base end portion 33a, is formed by the holding cylinder 34 fitted to the inner peripheral surface of the valve tubular portion 8b. It is held in close contact with the inner peripheral surface of the portion 8b. The valve body 33 includes a thin flexible portion 33b bent inward in the radial direction from the base end portion 33a, and a thick valve portion 33c connected to the front end of the flexible portion 33b. 33c is arranged so as to face the first and second valve seats 31, 32.

Thus, the valve portion 33c can be moved back and forth by the deformation of the flexible portion 33b, is seated on the first and second valve seats 31 and 32 when moving forward, and is received by the front end of the holding cylinder 34 when moving backward. . Between the valve element 33 and the input rod 29, a valve spring 35 that urges the valve portion 33c toward both valve seats 31 and 32 is contracted.

On the inner surface of the valve tube portion 8b, one end of the first port 20 is outside the first valve seat 31, and the second port is inside the valve seat 31.
One end of 23 is open. Further, the inside of the second valve seat 32 communicates with the atmosphere introduction port 27 through the hollow portions of the valve body 33 and the holding cylinder 34. Thus, the valve element 33, the valve spring 35, the first valve seat 31 and the second valve seat 32 constitute the control valve 26.

Between the input rod 29 and the holding cylinder 34, a return spring 37 for urging the input rod 29 toward the backward limit thereof is contracted. Input rod 29
The limit of the retreat is regulated by the stopper plate 38 screwed onto the input rod 29 so as to be adjustable forward and backward to come into contact with the inner surface of the end wall 9a of the rear extension cylinder 9. Therefore, when the stopper plate 38 is rotated, the screwing position between the stopper plate 38 and the input rod 29 is changed, so that the retreat limit of the input rod 29 can be adjusted back and forth. After the adjustment, the stopper plate 38 is fixed by tightening a lock nut 39 also screwed to the input rod 29. The stopper plate 38 is provided with a vent hole 40 so that the stopper plate 38 does not block the atmosphere introducing port 27.

An air filter 41 for filtering the air taken into the valve cylinder portion 8b from the atmosphere introducing port 27 is attached to the valve cylinder portion 8b around the input rod 29. The air filter 41 has appropriate flexibility so as not to hinder the relative displacement between the input rod 29 and the valve cylinder portion 8b.

The piston boss 8 is provided with a large cylinder hole 42 opening at the center of the front surface thereof and a small cylinder hole 43 having both ends open inside the large cylinder hole 42 and the valve cylinder portion 8b. Integrated with the valve piston 30 or the valve piston
A reaction force piston 44 abutting on 30 is slidably fitted, and in the large cylinder hole 42, an elastic piston 45 facing the reaction force piston 44 and an output piston 46 superposed on the front surface of the elastic piston 45. Is slidably fitted.

An output rod 47 is projectingly provided on the front surface of the output piston 46, and the output rod 47 is a piston 48 of the brake master cylinder M.
Connected to.

A coil-shaped return spring 49 is contracted between the retainer 50, which is in contact with the front surface of the piston boss 8, and the front wall of the booster shell 1, and the return spring 49 allows the piston boss 8, that is, both booster pistons. 4, 6 are always biased in the backward direction. Therefore, the retreat limit of both booster pistons 4 and 5 is
The protrusion 7b provided on the rear surface of the rear diaphragm 7 is restricted by coming into contact with the rear wall of the booster shell 1.

Moreover, the retainer 50 is provided with a notch 50a for arranging the communication pipe 22, and the protrusion 5 which is annular except for the notch 50a so as to regulate the outer periphery of the end portion of the return spring 49.
0b is projected. Thus, the retainer 50 prevents the one end of the communicating pipe 22 from coming out of the piston boss 8, and the return spring 49 prevents the other end of the communicating pipe 22 from coming out of the communicating cylinder 22.

Next, the operation of this embodiment will be described. First, in the rest state of the negative pressure booster B, as shown in FIG.
29 is located at the backward limit, and the control valve 26 causes the valve portion 33c to be seated on the first and second valve seats 31 and 32 to move the front working chamber 2b and the rear working chamber 3b to both the negative pressure chambers 2a, 3a and It is in a neutral state where it is cut off from any of the atmosphere introduction ports 27, and the negative pressure of the negative pressure source supplied through the negative pressure introduction pipe 19 is stored in both negative pressure chambers 2a and 3a by such a control valve 27. Both working chambers 2b and 3b have
A negative pressure, appropriately diluted by the atmosphere, is maintained. In this way, the front and rear booster pistons 4, 6 are connected to the front negative pressure chamber 2a.
A slight forward force is applied due to the difference in atmospheric pressure between the working chamber 2b and between the negative pressure chamber 3a and the working chamber 3b at the rear part, but these forward force and the elastic force of the return spring 49 balance each other, and The booster pistons 4 and 6 are stopped at a position slightly advanced from the backward limit.

Now step on the brake pedal 28 to brake the vehicle,
When the input rod 29 and the valve piston 30 are moved forward, both booster pistons 4 and 6 are initially immobile, so the second valve seat 32 is immediately separated from the valve portion 33c and the two working chambers 2b and 3b are introduced into the atmosphere introduction port. 27
Communicate with. As a result, the atmosphere flowing into the valve body 33 from the atmosphere introducing port 27 passes through the second valve seat 32 and then the annular groove 30.
a, the second port 23, the communication hole 21, and the communication pipe 22 and quickly introduced into both working chambers 2b and 3b, and these chambers 2b and 3b are connected to both negative pressure chambers 2a and 3b.
Since the pressure is higher than a, a large forward force based on the pressure difference between them is obtained, and both booster pistons 4 and 6 move forward with good response against the force of the return spring 49, and the brake master cylinder M via the output rod 47. The piston 48 of is driven forward. In this way, the brake master cylinder M can be operated without delay when the brake pedal 28 is depressed to brake the vehicle.

During such braking, the valve piston 30 moves forward together with the input rod 29 and contacts the elastic piston 45 via the reaction force piston 44.
Receives the reaction force of 6 and bulges and deforms toward the small cylinder hole 43 side,
Since a part of the reaction force is applied to the reaction force piston 44, the force is fed back to the brake pedal 28 side via the valve piston 30 and the input rod 29. By such a reaction force action, the operator can sense the output of the output rod 29, that is, the magnitude of the braking force.

When the output of the output rod 47 exceeds the boosting limit point due to an increase in the pedaling force applied to the brake pedal 28, that is, the input of the input rod 29, the valve piston 30 brings its front surface into contact with the piston boss 8, so that the entire input is applied to the valve piston. 30, piston boss 8,
Output rod 47 via elastic piston 45 and output piston 46
Will be transmitted to each booster piston 4,6
The sum of the forward force due to the atmospheric pressure difference and the forward force due to the input is output from the output rod 47.

Next, when the pedal force on the brake pedal 28 is released,
First of all, the input rod 29 is moved by the elastic force of the return spring 37 to the valve piston 30.
With this, the second valve seat 32 is seated on the valve portion 33c of the valve element 33, and the valve portion 33c is largely separated from the first valve seat 31, so that both working chambers 2b and 3b are connected to the first and second ports 20. , 3
It communicates with both negative pressure chambers 2a and 3a through 1,31.

Therefore, due to the strong suction action of the negative pressure source connected to the front negative pressure chamber 2a, the air occupying both working chambers 2b and 3b until now passes from the second port 23 to the first port 20 to the front negative pressure chamber. Pressure chamber 2a
Is rapidly inhaled, and the pressure difference around each booster piston 4, 6 disappears, and as a result, the booster pistons 4, 6
Moves backward by the elastic force of the return spring 48, and releases the operation of the brake master cylinder M.

When the input rod 29 returns to the retracted limit where the stopper plate 38 contacts the end wall 9a of the rear extension cylinder 9, the rear booster piston 6
Is temporarily returned to the retracted limit where the projection 7b of the rear diaphragm 7 is brought into contact with the rear wall of the booster shell 1, and this time the first valve seat
31 is seated on the valve portion 33c and the valve portion 33c is seated on the second valve seat 32.
At this point, the atmosphere is introduced again into both working chambers 2b and 3b, but if the booster pistons 4 and 6 slightly move forward due to the difference in atmospheric pressure caused between them, there is a gap between the second valve seat 32 and the valve portion 33c. The small gap in the column disappears and the control valve 26 is returned to the initial neutral state. In this way, the negative pressure diluted with the atmosphere is held in both working chambers 2b and 3b, and the negative pressure booster B is in the rest state shown in FIG.

In such a tandem-type negative pressure booster B, the connecting cylinder 12 provided on the front booster piston 4 has a front engaging portion 12a that engages with the piston boss 8 from the front side, and the piston boss 8 by bending. Are provided with rear engaging portions 12b, which are engaged from the rear side, and the inner peripheral bead 7a of the rear diaphragm 7 that wraps the inner peripheral edge of the rear booster piston 6.
However, the piston boss 8 is formed by interposing the rear engaging portions 12a.
The booster pistons 4 and 6 are connected to the piston boss 8 by engaging a stopper 17 that elastically pushes the inner peripheral bead 7a forward with the piston boss 8. For this reason, it is not necessary to divide the piston boss 8 into two parts. Therefore, the sealing member resulting from the two divisions is not necessary, and the number of parts can be reduced.

FIG. 3 shows another embodiment of the present invention, in which parts corresponding to those in the above embodiment are designated by the same reference numerals.

The piston boss 8'is provided with a flange portion 8c 'extending outward in the radial direction at the front end portion of a main body portion 8a' having a valve cylinder portion 8b 'at the rear portion and formed basically in a disk shape. ,
Connecting cylinder 1 connected to the center of front booster piston 4
A front engaging portion 12a 'that engages with the outer peripheral front edge of the flange portion 8c' from the front is provided radially inward in the axially intermediate portion of 2 ', and is provided over the entire circumference. A plurality of rear engaging portions 12b ', which engage with the outer periphery of the rear end of the flange portion 8c' by being bent, are provided at the rear end of the ′ so as to project. Moreover, the inner peripheral bead 7a of the rear diaphragm 7 that encloses the inner peripheral edge of the rear booster piston 6 has the rear engaging portion 12b '.
Is abutted on the rear surface of the flange portion 8c 'with the interposition of ..., and the stopper 17 engaged with the piston boss 8'bounces the inner peripheral bead 7a toward the franc portion 8c' side.

Also according to this embodiment, both booster pistons 4 and 6 are formed without dividing the piston boss 8'in the same manner as in the above embodiment.
Can be attached to the piston boss 8 ', and the seal member can be omitted to contribute to the reduction of the number of parts.

C. Effect of the Invention As described above, according to the present invention, a front engaging portion that engages with the piston boss from the front side and a plurality of rear engaging portions that can be bent to engage with the piston boss from the rear side are provided. A cylindrical connecting cylinder extending rearwardly is provided continuously at the center of the front booster piston, and the inner peripheral bead of the rear diaphragm that encloses the inner peripheral edge of the rear booster piston has the rear engaging portion interposed. Abutting against the piston boss from the rear, a stopper for elastically pushing the inner peripheral bead forward is engaged with the piston boss, and a seal member is interposed between the inner peripheral edge of the partition plate and the outer surface of the connecting cylinder. Therefore, the front booster piston is attached to the piston boss by engaging the rear engagement portion with the piston boss from the front side and bending the rear engagement portion to engage with the piston boss from the rear side. Can also By resiliently urging the rear toward the inner peripheral bead of the rear diaphragm by a stopper which engages the piston boss Sutonbosu, it can be engaged to the rear booster piston to the piston boss. Therefore, both booster pistons can be attached to the piston boss without splitting the piston boss, and the seal member that is required when splitting the piston boss is not required.

[Brief description of drawings]

1 and 2 show one embodiment of the present invention. FIG. 1 is a vertical sectional side view of a tandem type negative pressure booster, and FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a vertical sectional side view of a tandem type negative pressure booster according to another embodiment of the present invention. 1 ... Booster shell, 1c ... Partition plate, 2 ... Front shell chamber, 3 ... Rear shell chamber, 4 ... Front booster piston, 5 ... Front diaphragm, 6 ... Rear booster piston, 7 …… Rear diaphragm, 7a …… Inner circumference bead, 8,
8 '... Piston boss, 12,12' ... Connecting cylinder, 12a, 12a '
...... Front engaging part, 12b, 12b '…… Rear engaging part, 14 …… Seal member, 17 …… Stopper, 47 …… Output rod, B …… Tandem type negative pressure booster

Claims (1)

(57) [Scope of utility model registration request] 1. A booster shell (1) is provided with a partition plate (1c) for partitioning the inside into a front shell chamber (2) and a rear shell chamber (3), and a front diaphragm (5) on the rear surface. A front booster piston (4) that is polymer-bonded and a rear booster piston (4) that is rear-bonded with a rear diaphragm (7) are slidably supported on the partition plate (1c). In a tandem type negative pressure booster connected via a piston boss (8, 8 ') connected to an output rod (47), a front engaging portion (12a) engaging with the piston boss (8, 8') from the front side. , 12a ′) and the piston boss (8, 8 ′) can be bent to engage from the rear side with a plurality of rear engaging portions (12b, 12 ').
b ′) and a cylindrical connecting tube (12,1) that extends rearward.
2 ') is continuously provided in the central portion of the front booster piston (4), and the inner peripheral bead (7a) of the rear diaphragm (7) that surrounds the inner peripheral edge of the rear booster piston (6) is connected to the rear engaging portion ( 12b, 12b ') is interposed between the piston bosses (8, 8') from the rear, and the piston bosses (8, 8 ') elastically push the stopper (17) to elastically push the inner peripheral bead (7a) forward. ) Is engaged with the inner peripheral edge of the partition plate (1c) and the connecting cylinder (12, 12 ').
A tandem type negative pressure booster, characterized in that a seal member (14) is interposed between the outer surface and the outer surface of the.